In digital circuits, phase noise occurs due to errors in the clock edges of the digital circuit. Phase noise in a circuit may arise from various sources. For example, fluctuations in current and temperature affect the properties of charge carriers in the conductors of the circuit and introduce random noise. Phase noise also appears as additional frequency components due to short term fluctuations that show up as side bands to the desired signal frequency.
In digital circuits that are clocked using flip flops, the output noise of the circuit is determined by clock noise. When using flip flops, the output of the flip flop does not change until the next edge of the input clock signal. The clock is the mechanism that causes the flip flop to change states. Since phase noise is a measure of the variation in zero crossings of a signal, any noise present in the clock may be seen at the circuit output.
Alternative systems and methods for reducing phase noise in integrated circuits are desired.